Tracer projectile

ABSTRACT

A tracer projectile comprising a body having a rearwardly open recess with a pyrotechnic pack in the recess. The shell of the pack is located with radial clearance inside the recess. There are cooperating annular coned faces on the shell and in the recess. A threaded steel ring is screwed into the recess to the rear of the shell so that the axial thrust of the threaded ring on the shell will cause the pyrotechnic pack to be axially aligned by the cooperation of the annular coned faces. The threaded ring is provided with said radial slots on its side facing the shell.

rte States Patent 1 Muller et a1.

[ 51 Jan. 16,1973

[54] TRACER PROJECTILE Werkzeugmaschinenfabrik Oerlikon-Buhrle AG,Zurich, Switzerland [22] Filed: July 24, 1970 [2]] Appl. No.: 57,978

[73] Assignee:

[30] Foreign Application Priority Data Aug. 5, 1969 Switzerland..11860/69 [56] References Cited UNITED STATES PATENTS 1/1960 Barker..102/90X 4/1970 Grolly ..102/87X 3,272,126 9/1966 Edelman et al 102/90X 3,473,472 10/1969 Bliss et al ...l02/87 X 1,875,985 9/1932 Brandt 1..102/90 1,105,849 8/1914 Semple... 102/56 3,532,056 10/1970 Irion..102/56 3,176,617 6/1962 Brafford ....102/24 R 3,487,780 1/1970 Troenet a1. ...l02/87 X Primary Examiner-Benjamin A. Borchelt AssistantExaminerl-l. J. Tudor Attorney-Wenderoth, Lind & Ponack [57] ABSTRACT Atracer projectile comprising a body having a rearwardly open recess witha pyrotechnic pack in the recess. The shell of the pack is located withradial clearance inside the recess. There are cooperating annular conedfaces on the shell and in the recess. A threaded steel ring is screwedinto the recess to the rear of the shell so that the axial thrust of thethreaded ring on the shell will cause the pyrotechnic pack to be axiallyaligned by the cooperation of the annular coned faces. The threaded ringis provided with said radial slots on its side facing the shell.

3 Claims, 1 Drawing Figure PATENTEDJAN 16 I975 3.710.723

I III l g I l2 5 iii l3 Attorneys TRACER PROJECTILE The inventionrelates to a tracer projectile comprising a projectile body whichcontains a rearwardly open recess for a pyrotechnic pack.

In a tracer projectile of the specified kind already known in the artthe pyrotechnic pack is screwed into the rear end of the body of theprojectile. The rear end of the shell of the pack has a flange-likeenlargement of its external diameter that conforms with the caliber ofthe projectile. The enlargement extends the external contours of theprojectile body. In this known tracer projectile the body of theprojectile and the pyrotechnic pack must be exactly coaxial sinceotherwise difficulties would arise in fitting the cartridge to theprojectile. By pressing the pyrotechnic charge into its shell the lattermay be expanded, in which case the external threads on the pyrotechnicpack will no longer fit the internal threads in the body of theprojectile. Since the body of the projectile and the pyrotechnic packusually consist of different materials the screw connection alsoprevents thermal expansion between the two parts. Finally, thepyrotechnic pack may frac-' ture and splinter when exposed to the effectof the propellant gases when the tracer projectile is fired, and amuzzle velocity attachment on the barrel could also suffer damage.

It is the object of the present invention to eliminate the drawbacks ofthe prior art tracer projectile. Ac-' cording to the invention this isachieved by locating the pyrotechnic pack with radial clearance insidethe recess, providing the pack and the recess with cooperating annularconed faces and by screwing a threaded ring into the open end of therecess to the rear of the pyrotechnic pack in such manner that the axialthrust of the threaded ring applied to the pyrotechnic pack will resultin axial central alignment by virtue of the cooperation of the conedannular faces.

An embodiment of the proposed tracer projectile will be hereunder moreparticularly described with reference to the accompanying drawing.

A screw joint 2 connects the body 1 of a projectile to its cap 3. To therear of the cap 3 the body 1 of the projectile is provided with' acavity 4 which may contain, for instance, a blank charge. A recess 5extending into the body of the projectile from the rear comprises aforward portion 5a and a relatively enlarged rear portion 5b. Thetransition between the two portions 5a and 5b is formed by a conedsurface 6. The shell 7 of a pack containing a pyrotechnic charge 1 1 hasexternal dimensions that substantially fit into the recess 5 but leave asmall amount of clearance between the shell 7 and the inside wall of therecess 5. A coned face 8 on the shell 7 of the pack bears against acorresponding coned face 6 in the recess 5. The shell 7 is pushedaxially forwards by a retaining element 9 in the form ofa screw ringwhich is insertable into the rear end of the projectile body 1.

This ensures contact between the coned face 6 in the recess and theconed face 8 of the shell which is thus axially aligned. The retainingelement 9 has a central hole 16 and radial slots 10 on the side facingthe shell 7. Pressed into the shell 7 is a pyrotechnic charge 11 comprising three stages. Behind the charge 11 is an initiating charge 12.Rearwardly the shell 7 is closed by a disc 13 which is held in place bya shim .14 and an interposed sealing ring 15.

The above described tracer projectile functions as follows:

The propellant gases WhlCh discharge the pro ectile punch a hole intothe disc 13 and ignite the initiating charge 12 which in turn ignitesthe pyrotechnic charge 1 1. At the same time the propellant gases enterthe gap between the pyrotechnic charge 11 and the inside wall of theshell 7. In order to prevent these gases from partly or completelyejecting the pyrotechnic charge the propellant gases are divertedthrough the radial slots 10 in the retaining ring 9 into the clearancegap between the body 1 of the projectile and the outside wall of theshell 7. This enables the pressure above the end of the shell 7 tobe'fully equalized. If for any reason this pressure equalization shouldfail and the shell 7 should be fractured, allowing splinters to breakaway, these will still be prevented from falling out by the retainingring 9.

The propellant gases are sealed by the cooperating coned faces 6 and 8.These two faces 6 and 8 also function to align the shell 7 centrallyinside the recess 5. Consequently very close tolerances between theshell 7 of the pack and the recess 5 are not needed and the shell 7 hasfreedom to change its dimensions, as usually occurs after the case hasbeen pressed into position. Moreover, that part of the shell 7 whichextends forwards of the coned face 8 can freely move inside the bore 50when it thermally expands under the heat of the burning pyrotechniccharge.

We claim:

1. A tracer projectile comprising a body having a rearwardly openrecess, a pyrotechnic pack in said recess having a shell located withradial clearance inside said recess, cooperating annular coned faces onsaid shell and in said recess, a threaded ring screwed into said recessto the rear of said shell so that the axial thrust of said threaded ringon said shell will cause said pyrotechnic pack to be axially aligned bythe cooperation of said coned annular faces, radial slots providedbetween said threaded ring and said shell.

2. A tracer projectile according to claim 1 wherein said threaded ringis provided with said radial slots on its side facing said shell.

3. A tracer projectile according to claim 1 wherein said annular conedsurface on said shell is provided at the rear end of said shell so thatthe major part of the shell extends freely into said recess.

1. A tracer projectile comprising a body having a rearwardly openrecess, a pyrotechnic pack in said recess having a shell located withradial clearance inside said recess, cooperating annular coned faces onsaid shell and in said recess, a threaded ring screwed into said recessto the rear of said shell so that the axial thrust of said threaded ringon said shell will cause said pyrotechnic pack to be axially aligned bythe cooperation of said coned annular faces, radial slots providedbetween said threaded ring and said shell.
 2. A tracer projectileaccording to claim 1 wherein said threaded ring is provided with saidradial slots on its side facing said shell.
 3. A tracer projectileaccording to claim 1 wherein said annular coned surface on said shell isprovided at the rear end of said shell so that the major part of theshell extends freely into said recess.